Reversal inhibiting engine starter with centrifugal brake



June 18, 1963 w. EFFINGER, JR

REVERSAL INHIBITING ENGINE STARTER WITH CENTRIFUGAL BRAKE 2 Sheets-Sheet1 Filed Feb. 23', 1961 INVENTOR w sssggm efim ATTORNEY June 18, 1963 w.L. EFFINGER, JR 3,094,109

REVERSAL INHIBITING ENGINE STARTER WITH CENTRIFUGAL BRAKE Filed Feb. 23,1961 2 Sheets-Sheet 2 INVENTOR 58. 8% e4, 5 2. BY

Patented June 18, 1963 3,094,109 REVERSAL INHIBITING ENGINE STARTER WITHCENTRIFUGAL BRAKE William L. Elfinger, Jr., Harnden, Comm, assignor toThe A. C. Gilbert Company, New Haven, Conn, a corporation of MarylandFiled Feb. 23, 1961, Ser. No. 91,032 12 Claims. (Cl. 123-179) Thisinvention relates to starting devices for internal combustion enginesparticularly of the very small sizes used to drive model airplanes,boats, toy vehicles and the like.

It has been proposed to start such engines by manually tensioning aspiral spring and then releasing it to whirl the engine shaft in runningdirection. The spring has been so tensioned by a few spring windingmanually impelled turns of the engine-driven rotor in backward directionopposite to the intended direction of engine running. In the case of atoy airplane engine, the rotor is a driven propeller fixed to the engineshaft and serving as a crank handle by which to wind up the spring forengine starting action when manually released. Obviously when oncestarted and engine driven the propeller shaft must be able to continueits engine driven rotation in the proper direction free of hindrance bythe spring.

Many engines of the type here most concerned can fire as readily in onedirection of running as in the other, depending on minute variations inthe time and speed of the crankshaft with respect to occurrence of theexplosion when the piston reaches and passes top center in the stroke ofthe crankshaft.

Thus an engine of this type after starting to run in one direction can,upon sufficient reduction of speed incurred by increase in load, orfailure of fuel supply, automatically reverse its direction of runningfor lack of sufficient momentum in the moving parts to carry the pistonfully over top center at the time the engine fires.

It has been proposed to accomplish such automatic freeing of the engineshaft from the driving action of the spring by permanently anchoring oneend of the starter spring to the engine body and permitting the oppositeend of the spring to uncouple automatically from its rotor drivingconnection. Hence, prior to the present improvement, it has beenproposed that the starter spring remain stationary with the engine bodyafter having functioned to start the engine.

In this previous way of starting engines there has been no safeguardagainst firing of the engine in a way that can run the engine in thewrong direction. Frequent need of corrective stopping and restarting ofthe engine has been taken for granted.

An object of this invention is to provide a spring action startingdevice of required simplicity, low cost, durability, and positiveness ofaction which positively restricts running of the engine to a singleintended forward direction of rotation at all times.

A related object is similarly to inhibit running of the engine inreverse or backward direction even if the engine attempts to reverse itsdirection of running at any time after having been started initially inthe forward or right direction.

Another object is to enable the starter spring to rotate bodily inunison with the engine driven rotor instead of remaining stationary withthe engine body, so that the weight of the revolving starter parts mayserve as a fly-wheel on the engine shaft with benefit to the smoothnessof running of the engine.

Another object is to interpose improved brake means between the starterspring and the engine body as part of connections operativelycouplingthe engine driven rotor to the engine body.

Another object is to provide such brake means arranged to perform itsautomatic coupling and uncoupling action by the action of centrifugalforce.

Another object is to enable the engine driven rotor to become uncoupledfrom the engine body before it has completely dissipated the energystored therein by its manual prewinding for starting the engine.

The foregoing and other objects of the invention will become apparentfrom the following description of successful embodiments of theimprovements having reference to the appended drawings wherein:

FIG. 1 is a perspective external view of a miniature single cylinderinternal combustion engine rigged to drive a toy airplane propeller andincorporating starting devices embodying the invention.

FIG. 2 is a somewhat similar view of the same engine with the propellerand starting devices removed to expose the crankshaft of the engine.

FIG. 3 is a perspective view of the starting devices removed from thepropeller and the engine parts of FIGS. 1 and 2.

FIG. 4 is a fragmentary enlarged side elevation of the engine, propellerand starting devices in FIG. 1 showing the starting device and propellerhub in section on angularly related radial planes 4-4 in FIG. 5.

FIG. 5 is a view taken in section on the plane 5-5 in FIG. 4 looking inthe direction of the arrows.

FIG. 6 is a view taken in section on the plane 6-6 in FIG. 4 looking inthe direction of the arrows.

FIG. 7 is a view similar to FIG. 5 showing on an enlarged scale amodified embodiment of the invention.

FIG. 8 is a view taken in section on the plane 8-8 in FIG. 7 looking inthe direction of the arrows.

FIG. 9 shows a modified construction of the centrifugal clutch of FIGS.7 and 8.

FIG. 1' 0 shows a further modified construction of centrlifugal clutchtaken partially in section on a diametral p ane.

FIG. 11 is a view taken in section on the plane 11--11 in FIG. 10looking in the direction of the arrows.

FIG. 1 represents the body 12 of a typical miniature single cylindercombustion engine equipped at each side with a lug 13 containing holes14 for mounting the engine removably on the framework of a toy airplane(not shown) or other small craft, boat or vehicle to be powered by theengine. Engine body 12 conventionally includes a power cylinder 15, anair intake 16, a fuel intake 17, exhaust cooling fins 18 and thecrankcase 19.

The crankcase portion of the engine body includes bearing structure 2 1in which the crank shaft 20 is journalled. Such structure comprises acylindrical boss containing an external notch 24 providing a stationarydetent shoulder 22. The crankshaft projects from its bearing to receivefixedly on its knurled portion 30 the hub 31 of an engine driven rotorincluding the hollow spring barrel 32. Barrel 32 always turns in unisonwith shaft 20 and houses between its rim- 33- and the stationary boss 21of the engine body a spirally coiled engine starting band spring 34having its outer end permanently secured to the drum ring 33 by a rivet37 and carrying fixed to its inner end by rivets 36 a weighty catch orlatch 35. Spring 34 is so resiliently conditioned that it normallybiases the latch 35 radially inward into wiping contact with boss 21 sothat the latch automatically seeks and becomes seated in the stationarynotch 24 in hooked engagement with a keeper for-med by the detentshoulder 22.

Latch 35 has sufiicient weight to be sensitive to centrifugal force andthereby can be flung radially outward away from hearing boss 21 andclear of the notch shoulder 22 by rapid speed of rotation of barrel 32with engine shaft 20' when such force is great enough to overcome. the.natural bias in spring 34 and cause flexure of the. spring in anunwinding direction. Thus the engagement and disengagement of catch orlatch 35 with notch shoulder 22 of the keeper functions automatically inresponse to variation in speed of the engine shaft in such manner thatwhen stationary, or revolving at relatively slow speed, the turning ofshaft 20 counterclockwise in FIG. (clockwise in FIGS. 1 and 6) will actto wind up spring 34 to a limited extent and store tension therein whichsubsequently can operate automatically to whirl shaft 20 incounterclockwise or forward running direction in FIGS. 1 and 6(clockwise in FIG. 5 This will whirl the crankshaft so rapidly past topcenter position of the piston that starting of the engine ordinarilywill take place in the intended forward direction, If it does not, andif; faulty firing causes accidental starting of the engine in reversedirection, the catch 35 immediately reengages with notch shoulder 22 andchecks turning of the shaft in such wrong direction whereupon themomentum of the rotor parts such as 32 turning in wrong direction willautomatically repeat a winding up of the spring so that when the backfiring force of the engine is spent the spring will again automaticallyfunction to whirl the shaft in forward or engine running direction andthereby restart the engine in proper direction without manual attention.Such automatic checking of backward rotation followed by enginerestarting automatic drive of the shaft in forward direction will occurat any time when temporary reduction of speed results in accidentalback-firing of the engine while it is running.

In the drawings the load to be rotated by crankshaft 20 is representedby the propeller 49 of a toy or model aircraft whose hub 41 is fixedlyinterlocked with spring barrel 32 by the mutual engagement of radiallydisposed and mating ridges and grooves 42 on the propeller hub and 43 onthe mating face of the barrel hub 31. The propeller is removably securedon the crankshaft 20 by a retaining nut 44 and slip washer 45.

In starting an engine by use of the invention when embodied in the formof mechanism shown in FIGS. 1 to 6, inclusive, the engine is assumedfirst to be, at rest with the catch 35 biased against the stationarybearing boss 21, ready automatically to enter the notch 24 in releasablehooking relation to notch shoulder 22. A finger of the operators hand isapplied to impeller 40 in a manner to swing it a few turns clockwise asviewed in FIG. 1. The catch 35 will seek and enter the notch 24 and beheld stationary by notch shoulder 22 while a subsequent few turns of thespring barrel 32 clockwise in FIG. -1 prewind or store up enginestarting tension in the spring. The operators finger tip, can then bewithdrawn abruptly and safely from the extreme end of the propellerblade. Spring 34 will immediately deliver its stored up energy to therotor 32 by rapid unwinding fiexure which whirls spring barrel 33 a fewturns clockwise. Engine shaft 20 thereby becomes effectively cranked inengine running direction causing the engine to fire and take over thedrive of the shaft, the spring, spring barrel and the propeller, all inunison.

Thereupon these engine driven rotor parts pick up and run ahead of theinitial rotor driving action of the starter spring. Catch 35 will beflung by centrifugal force radially outward away from its anchoredretention by keeper 22 as permitted by flexure of the starter spring 34and Will be maintained thus freed from engagement with bearing boss 21so long as the engine continues to impart rapid; rotation to the springas the latter travels in unison with the engine driven rotor.

In the absence of the action of centrifugal force, spring 34 could notbe relied on to insure starting or automatic restarting of the engine.in correct or forward direction in the event of backward firing of theengine. However the action of such centrifugal force is not necessaryfor freeing catch 35 from notch shoulder 22 merely l :r i 4 to permitengine drive of the propeller in forward direction, namelycounterclockwise in FIGS. 1 and 6 (clockwise in FIG. 5) because thecatch can always ride freely out of notch 24 in that direction.

The above described characteristics of a starter operating on theprinciples of this invention differ from comparable starters, asheretofore constructed and functioning, in that the starter spring inpreviously known starters has been disenabled to operatively connect theengine driven rotor and the engine body by a break in transmission ofspring power to the engine driven rotor instead of by breaking theretentive anchorage of the spring to the stationary engine body, and thedisenabling of the starter spring can occur before it has becomecompletely unwound or deenergized. The benefits arising from the presentimprovements are derived in part from ability of the starter spring tobecome thus automatically freed by centrifugal force from anchorage tothe engine body even while the spring remains partially energized.

In the modified construction shown in FIGS. 7 and 8, the radiallyoutermost end of the starter spring 34 is permanently secured by a rivet37 to the rim 33 of an engine driven rotor which includes the springbarrel 32 as in FIGS. 1 to 6. But in place of a catch like 35 floatingwith the radially innermost end of spring 34 the inner spring end ispermanently secured to the rim 49 of a cup shaped brake ring 50 by arivet 51. This ring has a loose running fit in a circumferential bearinggroove 52 on the external cylindrical surface of the boss 21 of theengine body 19 thus deriving axial thrust from the side shoulders ofsuch groove. Within the annular space intermediate the rim 49 of thebrake ring 56 and the bearing boss 21' there are pivotally carried twoor more detent pawls 53 independently swingable on pivot studs 54 fixedin the web wall 55 of brake ring 50, preferably at diametricallyopposite sides of the ring respectively.

Each pawl 53 is individually biased by a short leaf spring 56 fixedthereon and bearing outward against the inner surface of ring rim 49 ina manner constantly to urge the hook head 57 of the pawl toward thestationary bearing boss 21' and into releasable latching engagement witheither of the shoulders 22 of notches 24 in the stationary bearing boss.Each pawl head 57 is weighted by an insert 58 of substance such as leador steel having heavier specific gravity than the material of the pawlwhich may be nylon. Such weighting will aid in enabling centrifugalforce exerted on the pawl head to overcome the resilient resistance ofpawl springs 56 and swing the pawl counterclockwise in FIG. 7 and out ofdetentive engagement with notch shoulder 22 and maintain suchdisengagement as long as brake ring 50 is rotated by engine drive withsufiicient angular speed to generate the required centrifugal force.

The pawls 53 are sometimes referred to herein as the latch elements of acentrifugal brake. A simplified form of such pawls is shown at 53' inFIG. 9 wherein the pawl thrusts against, instead of pulling on, thekeeper shoulder 63 of notch 62 in the bearing boss 61 of the enginebody. This keeper shoulder is inclined at a slightly obtuse angle ratherthan an acute angle with respect to tangency to its circle of rotation.

In FIG. 9 one of the pawls 53' is shown drivingly engaged with itskeeper shoulder 63 while the other is shown disengaged therefrom merelyto illustrate the engaged and disengaged positions between which thepawl can swing. It will be observed that the eccentric portion of thepawl body that engages the keeper shoulder 63 is more massive than inthe pawls 53 of FIG. 7 whereby to be self reactive to gravity andcentrifugal force so that pawls 53 will fall into engagement withnotches 62, and automatically withdraw therefrom, without need of pawlbiasing springs such as 56 in FIG. 7. Pawls such as 53' are preferablymade very loosely swingable about their pivot studs 54.

FIGS. 10 and 11 show a still further modified construction wherein ring68 drives brake ring 67 and together therewith and can be anchoredagainst rotation at respectively dififerent speeds as well as inpredetermined direction, by a claw tooth or teeth 66 projecting from andforming part of a brake ring 67. This provides a claw type ofcentrifugal brake in which ring 67 is joined by leaf springs 73 inspaced and axially slidable relation to clutch ring 68, which latter isarranged and connected to function in relation to the other parts of thestarter like part 50 in FIGS. 7 to 9 inclusive.

In FIGS. 10 and 11 an axially facing shoulder 69 on bearing boss 70 isprovided with as many notches 71 having keeper shoulders 72 as there areclaw teeth 66 on brake ring 67, all being equally spacedcircumferentially. Brake ring 67 is joined to ring 68 by two or morepairs of the aforesaid radially extending bowed spring leaf arms 73which at their radially outermost ends are fixed together and fixedlycarry weights 74. When brake ring 67 is driven to rapid rotation throughspring arms 73 by ring 67 the radially outward pull of weights 74 on thebowed spring arms 73 in response to centrifugal force tend to straightenthe spring arms with consequent drawing of brake ring 67 toward the leftin FIG. 10'. Thereupon all of the claw teeth 66 become disengaged fromthe stationary bearing boss notches 71 and free brake ring 67 fromanchorage coupling to the body of the engine. In the absence ofsufficiently high speed of rotation of ring 68 the resilience in springarms 73 restores the brake ring 67 into anchored engagement with thestationary bearing boss 7 0 of the engine body.

Certain advantages arise from maintaining the starter spring permanentlyconnected to the engine driven rotor so as always to travel bodily inunison therewith whether the brake is a centrifugal clutch or simply aone-way holding brake permitting the engine driven rotor to outrun theinitial driving action of the starter spring in one direction. These andall other variations of the exact kind and arrangements of parts hereinproposed are intended to be covered by the appended claims if comingwithin a broad interpretation of their terminology.

What is claimed is:

l. The combination with the driven rotor and stationary body of aninternal combustion engine of, connections for elastically coupling saidrotor to said engine body comprising at least in part, engine startingresilient means permanently attached to said rotor to travel in unisontherewith, and positively self latching brake means operativelyinterposed between said resilient means and said engine body operativeautomatically to couple and uncouple said rotor and engine body inrespectively opposite directions of rotation of the former relative tothe latter.

2. The combination with the driven rotor and stationary body of aninternal combustion engine of, connections for elastically coupling saidrotor to said engine body comprising at least in part, engine startingresilient means permanently attached to said rotor to travel in unisontherewith, and self latching brake means including a keeper in fixedrelation to said engine body and a catch cooperative with said keepermounted to revolve with said rotor and shiftable relatively thereto inadirection automatically to couple and uncouple said rotor and enginebody responsively respectively to changes in centrifugal force atdiiferent angular speeds of rotation of said rotor relative to saidengine body.

3. The combination defined in claim 1, in which the said resilient meansis a coiled starter spring and the said brake means comprises astationary keeper on the said engine body cooperative with a latchcarried on an end 6 of said spring in position to be permitted byflexure of said spring to engage retentively with and to disengage fromsaid keeper. 1

4. The combination defined in claim 3, in which the said latch isweighted in a manner to be caused to escape automatically from retentiveengagement with the said keeper by centrifugal force exerted on the saidstarter spring and generated by relatively high angular speeds of saidrotor and said spring in unison.

5. The combination defined in claim 4, in which the said starter springis statically conditioned by its own resilience to bias the said latchin direction to seek and automatically resume retentive engagement withthe said keeper when relieved of the said centrifugal force after beingdisengaged thereby from said keeper.

6. The combination defined in claim 1, in which the said brake meanscomprises, a stationary keeper on the engine body, a brake ring drivablyconnected to the said engine starting resilient means, a rotor bearingconfining said brake ring to circular movement coaxially of the saidengine driven rotor, and at least one latch element driven by the saidbrake ring in shiftable relation thereto in a circular path enablingsaid element by shifting position relatively to said brake ring toengage retentively with and disengage from the said keeper onrespectively different occasions.

7. The combination defined in claim 6, in which the said latch elementis a detent pawl pivotally mounted on the said brake ring in swingablerelation thereto.

8. The combination defined in claim 7, in which the said detent pawl isshaped and disposed in respect to its mounting on the said brake ring tobe urged to shift relatively thereto in a direction to disengageautomatically from the said keeper responsively to centrifugal forcegenerated by rotation of said brake ring.

9. The combination defined in claim 8, together with a spring reactivebetween the said brake ring and the said detent pawl urging the latterin direction to engage detentively with the said keeper.

10. The combination defined in claim 6, in which the said latch elementis shiftable in relation to the said brake ring in a direction parallelwith the axis of rotation of the latter.

11. The combination defined in claim 10, together with a governor springconnecting the said latch element to the said brake ring in a manner tobias said element toward the said keeper, and a weight carried by saidgovernor spring in a manner to flex said governor spring in direction todisengage said latch element from retentive engagement with said keeperin response to centrifugal force generated by rotation of said brakering.

12. The combination defined in claim 1, in which the said direction ofrotation in which the said self latching brake means is operativeautomatically to uncouple the said rotor and the said engine body is thesame rotary direction as that in which the engine is started to run bythe power of the said resilient means, whereby said rotor must be turnedin the opposite direction to tension said resilient means to deliversaid power.

References Cited in the file of this patent UNITED STATES PATENTS2,855,070 McRoskey et a1. Oct. 7, 1958 2,869,682 De Millar Jan. 20, 19592,876,866 Barr Mar. 10, 1959* 2,927,660 De Groat Mar. 8, 1960

2. THE COMBINATION WITH THE DRIVEN ROTOR AND STATIONARY BODY OF ANINTERNAL COMBUSTION ENGINE OF, CONNECTIONS FOR ELASTICALLY COUPLING SAIDROTOR TO SAID ENGINE BODY COMPRISING AT LEAST IN PART, ENGINE STARTINGRESILIENT MEANS PERMANENTLY ATTACHED TO SAID ROTOR TO TRAVEL IN UNISONTHEREWITH, AND SELF LATCHING BRAKE MEANS INCLUDING A KEEPER IN FIXEDRELATION TO SAID ENGINE BODY AND A CATCH COOPERATIVE WITH SAID KEEPERMOUNTED TO REVOLVE WITH SAID ROTOR AND SHIFTABLE RELATIVELY THERETO IN ADIRECTION AUTOMATICALLY TO COUPLE AND UNCOUPLE SAID ROTOR AND ENGINEBODY RESPONSIVELY RESPECTIVELY TO CHANGES IN CENTRIFUGAL FORCE ATDIFFERENT ANGULAR SPEEDS OF ROTATION OF SAID ROTOR RELATIVE TO SAIDENGINE BODY.